Mineralogical and petrological study of the ground stone artifacts from
the Neolithic Settlement of Avgi, Kastoria, NW Greece

The systematic geo-archaeological study of the lithic artifacts and objects from the Neolithic Settlement of Avgi at Kastoria enables the investigation of the specific usage characteristics of the various raw materials. Furthermore, it sheds light to the understanding of selection methods and the management of raw materials by the Neolithic Avgi inhabitants. The mineralogical, petrological and geochemical study of the archaeological material greatly contributes to this effort (Melfos & Stratouli 2017). In addition, the investigation of the natural availability of these raw materials in the region adds the concepts of space and time in the scientific research. It provides information on the spatial spreading in search of raw materials and on the required time to approach these sources. Thus, the most significant goal of this study is to determine and identify the sources of the raw materials used by the inhabitants of Neolithic Avgi.

Figure 1. Representative samples of lithic artifacts and tools, which emphasize the variety of raw materials used by the neolithic inhabitants of Avgi: a. Grinding tool made of sandstone, b. Marl sandstone slabs retrieved during the field survey at the broader region, they are similar to the slabs found at the excavation, c. Percussion tool made of gabbro, d. Axe made of serpentinite, e. Axe made of ophicalcite, f. Axe made of serpentine, g. Bead made of botryiod malachite, h. Bead made of amber, i. Fragments of a marble bowl, j. Red pigment probably from iron-rich bauxite.

Since September 2014, more than 3000 lithic findings have been studied. They are mainly lithic artifacts and tools made of a variety of rocks and minerals (Fig. 1).

The majority of the studied objects are grinding tools (for preliminary results of their petrographic study see Bekiaris et al. 2015), which are mainly made of sandstones and conglomerates of various size, mineralogical composition, grain size and hardness (Fig. 1a). Worth mentioning is the use of marl sandstone slabs, probably used for cooking due to their refractory properties (Fig. 1b).

Many tools are made of boulders retrieved from the ophiolitic rock sequences of the region (Fig. 1c, d, e). Percussion tools are made of gabbro or infrequently ophicalcite, two massive and hard rocks, while cutting tools (e.g. axes, adzes, and chisels) are made almost entirely of serpentinite. Noteworthy is also the presence of small, lightly transparent cutting tools made of the comparatively softer serpentine (Fig. 1g).

Of particular importance are the excavation findings made of non-local materials. These include two beads of malachite, where the typical botryoid mineral structure is observable (Fig. 1), a bead of amber (Fig. 1e) and two fragments of marble vessels (Fig. 1j). Another important finding is a piece of red pigment, which bears multiple friction traces (Fig. 1k). This material comes probably from the local iron-rich bauxite occurrences. Red residues were also found as encrustations on grinding tools, implying that these ore nodules were used as pigments, however, additional mineralogical and geochemical investigations are necessary to support this suggestion.

The above mentioned data reveal the integrated, empirical knowledge of the properties and capabilities of these raw materials by the neolithic inhabitants of Avgi, as well as their optimal use in order to fulfill everyday needs and standards of living. The geological field survey at the broader region has highlighted possible sources of origin for all the local raw materials. The basement of the neolithic settlement of Avgi is composed of sedimentary rocks, mainly sandstones, marls and conglomerates, of the Ontria and Tsotyli Formations of the Mesohellenic Trough (Fig. 2). The Tertiary (~ 56-5 Ma) Mesohellenic Trough is a SE-E trending massive basin formation, which spreads from southeastern Albania to Thessaly, locally exceeding 5 km in thickness. It was formed and filled with sediments during the latter stages of the Alpine Orogeny.

The second group of rocks located in the area belongs to the Pelagonian geotectonic Zone. These rocks are the bedrock of the Mesohellenic Trough. They include Paleozoic metamorphic rocks such as gneisses, schists, amphibolites, metamorphosed granites and plutonic rocks, as well as Mesozoic carbonates, granites and ophiolitic rocks.

Highly significant is the presence of Holocene (<100,000 years) alluvial and deltaic deposits of the Aliakmonas river. These deposits, along with the lacustrine deposits of the lake of Kastoria, cover a large part of the region. Their study reveals the complex, changing and varied supply of the Holocene palaio-depositional environment. It seems that these deposits serve a great role over time for the inhabitants of Neolithic Avgi as secondary sources of raw materials.

Figure 2. The geological map of the broader Avgi region (based on Bekiaris et al., 2015)..

Various analytical methods have been already applied and some will be implemented in the near future in order to further strengthen the conclusions of this research. Thin sections of selected archaeological findings and several field samples were studied under microscope for mineralogical and comparative purposes. Furthermore, the forthcoming chemical analyses will result in the quantitative and qualitative determination of the main and trace elements of the selected samples, as well as verify our theories regarding the origins of raw materials. Moreover, sophisticated analytical techniques will reveal detailed information about the type and the source of the pigments and perhaps their production methods. Finally, petrographic and isotopic studies will probably indicate the region of origin of the marble vessels. This dataset will provide significant information about the size of the trading network of Neolithic Avgi.
 

References 

Bekiaris, T., Stergiou, Ch., & Theodoridou, S. 2017. Making choices in a Neolithic landscape: raw materials and ground stone technology in Neolithic Avgi, NW Greece, In: Communities, landscapes, and interaction in Neolithic Greece, Proceedings of the International Conference, Rethymno 29-30 May, 2015, (Sarris, A., Kalogiropoulou, E., Kalayci, T., & Karimali, L., eds.), International Monographs in Prehistory, United States of America: 415-433

Melfos V. and G. Stratouli, 2017. Raw material and provenance identification of Late Neolithic and Chalcolithic chert artefacts from Drakaina Cave, Kephalonia, through petrographic and geochemical analysis. Studies in Mediterranean Archaeology, vol. CXLIV, Astroms Editions, Uppsala 2016.

January 2017

Christos L. Stergiou MSc Geologist, PhD Candidate
christer@geo.auth.gr

Stella Theodoridou, Geologist
stheo@hotmail.gr